1. Field of the Invention
The invention relates to a transistor circuit comprising an input terminal for receiving an input signal, an output terminal for providing a buffered output signal in response to the input signal, a first transistor having a control electrode coupled to the input terminal, a first main electrode coupled to the output terminal and a second main electrode, and a first bias current means coupled to the first main electrode for supplying a first bias current to the first transistor.
2. Description of the Related Art
Such a transistor circuit is the well known follower and is widely used as a buffer for driving capacitive loads. For example in sampling circuits, e.g. Track and Hold Circuits or Sample and Hold Circuits, where the signal is stored in a capacitor, some drive capacity is required in order to store the input signal with sufficient accuracy at the desired signal speed. A very basic circuit for this purpose is the follower. A bipolar implementation of the follower including the capacitive load is shown in FIG. 1. Due to the non-linear voltage-to-current transfer characteristics of a transistor the output signal across the capacitive load can be expressed as a level shifted version of the input signal plus a series of even harmonic distortion terms and a series of odd harmonic distortion terms. Using a differential circuit topology the even harmonic distortion terms can be suppressed and theoretically be eliminated supposing ideal matching between the duplicated circuit parts. However, the odd harmonic distortion terms cannot be suppressed in this way.